Push-off & Safety

[Bpx4st]

I guess my question for the OP would be....were there any "symptoms" exibited by the gun that would indicate there was a problem with the single action prior to your test for push off?

The S&W armorer's manual describes the pressure used to test the hammer trigger interface as "nominal". (whatever that is) Having some experience with testing for, and repair of this condition, I would estimate this pressure as 4 - 6 pounds. Excessive pressure should not be used as this can damage the very sharp bevel on the trigger.

Revolvers suffering from push off will usually also exhibit specific symptoms of the problem, including a "mushy" (opposite of crisp) and very light SA trigger let off.....below 2.5 lbs.

Symptoms can manifest themselves after years and years of heavy use, build up of dirt, debris or old/improper lubricants.....or from modification of factory installed components, including the mainspring, mainspring strain screw, rebound slide spring, or the hammer/trigger SA interface. (or combination of these factors)

If there are no other obvious mechanical or felt symptoms indicating a problem with the hammer and trigger, and the internals are confirmed clean and properly lubricated, perhaps a better test to check the integrity of the single action for most revolver owners would be to simply use a quality trigger pull gauge. Factory minimum recommended SA pull is 3 pounds.

As I stated in my first post, I estimated the push at about 7-10 lbs., which apparently, is more than needed for the test. As another poster suggested, it shouldn't break at any push (at least, that's how I interpreted it), so that concerned me. Now, you say 4-6lbs. should be a better indicator. It's not exhibited any other signs like a mushy pull or anything. I had just read about push-off on another article & thought I would check mine.
I haven't had the cover plate off but I can to do a visual & check the spring screw for any backing off but I'm not confident enough to start taking things out & checking for any chipped or rounded edges. I haven't just kept pushing to check it so I doubt I've overdone it to the point of MAKING it fail. Like I said earlier, I did check it this morning with lighter pressure with no problems, so hopefully, I just need to quit reading so much & creating problems that may not exist...but I love reading about my guns.

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[M19-5]

Hammer push-off test is one of many checks I use before buying a used revolver.
It is a safety check.
If you have a bathroom or postal scale of some sort, place the muzzle on the scale plate, push down on the hammer spur and see how much pressure it takes before it pushes off.
This is a better way to check than guessing how much pressure you are using with your thumb.
Jerry Kuhnhausen states if you can get to 16#'s, you do not have push-off.(so no need to go any further).
Jerry also states that "some experts" state 10-12#'s.
I am in the 10-12# camp and never had a safety issue.
I have worked on some friends revolvers in the past that you could just slightly push or look at it wrong and the hammer would fall.(not safe at all).

Clarence

 

[Bpx4st]

Hammer push-off test is one of many checks I use before buying a used revolver.
It is a safety check.
If you have a bathroom or postal scale of some sort, place the muzzle on the scale plate, push down on the hammer spur and see how much pressure it takes before it pushes off.
This is a better way to check than guessing how much pressure you are using with your thumb.
Jerry Kuhnhausen states if you can get to 16#'s, you do not have push-off.(so no need to go any further).
Jerry also states that "some experts" state 10-12#'s.
I am in the 10-12# camp and never had a safety issue.
I have worked on some friends revolvers in the past that you could just slightly push or look at it wrong and the hammer would fall.(not safe at all).

Clarence

I did the bath scale (acurate as heck, I know) & it said 11lbs. It was a digital scale so it held the reading for a couple of seconds. I probably will still have a smithy check it out. I like to err on the safe side.
I appreciate the imput.

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[M19-5]

Glad to assist when I can.
Keep us updated.
Stay safe and shoot well.

Clarence

 

[armorer951]

Have you checked the SA trigger pull rate?

 

[Bpx4st]

Have you checked the SA trigger pull rate?

I don't own or have access to a gage. Once again, just a guess but I figure about 3 lbs.

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[MikeR90S]

I guess my question for the OP would be....were there any "symptoms" exibited by the gun that would indicate there was a problem with the single action prior to your test for push off?

The S&W armorer's manual describes the pressure used to test the hammer trigger interface as "nominal". (whatever that is) Having some experience with testing for, and repair of this condition, I would estimate this pressure as 4 - 6 pounds. Excessive pressure should not be used as this can damage the very sharp bevel on the trigger.

Revolvers suffering from push off will usually also exhibit specific symptoms of the problem, including a "mushy" (opposite of crisp) and very light SA trigger let off.....below 2.5 lbs.

Symptoms can manifest themselves after years and years of heavy use, build up of dirt, debris or old/improper lubricants.....or from modification of factory installed components, including the mainspring, mainspring strain screw, rebound slide spring, or the hammer/trigger SA interface. (or combination of these factors)

Since the term "nominal" pressure is subject to a wide range of interpretation............if there are no other obvious mechanical or felt symptoms indicating a problem with the hammer and trigger, and the internals are confirmed clean and properly lubricated, perhaps a better test to check the integrity of the single action for most revolver owners would be to simply use a quality trigger pull gauge. Factory minimum recommended SA pull is 3 pounds.

Please explain how the rebound spring can affect push off? Not being argumentative, just trying to learn.

Mike

 

[armorer951]

The rebound slide spring not only performs the essential task of resetting the action and returning the trigger and other components to their "stand by" positions, but it also holds necessary tension on the trigger bevel when the action is cocked SA.
The trigger bevel is the very sharp, angled edge at the top of the trigger that interfaces with the SA cocking notch on the hammer. When the hammer is cocked SA, the tension from the rebound spring, working together with the pressure exerted by the mainspring, keeps the point of contact (bevel) standing at rest under tension on an approx .008" wide ledge called the cocking notch, or SA notch.

Decreasing the stardard length (OEM) rebound spring tension does not in and of itself cause push off, but merely lowers the threshold where the push off can occur. All other things being equal, it makes the interface less viable, if you will, when viability is evaluated purely in terms of SA trigger pull weight.
Other factors also negatively effect the viability of this interface, including dirt and debris, unsuitable lubricants, wear and tear, modifications, etc.

It's important to consider the role of the rebound spring not only in terms of it's job in trigger return, but also the important role in SA integrity as well.

 

[MikeR90S]

Thank you for the excellent explanation. That makes a lot of sense but seems to be largely ignored in how low can you go discussions about rebound springs.

Mike

 

[Bpx4st]

Armorer951, I thought you gave a very intelligent & insightful explanation. I'm not saying I understand it all but that's part of the learning curve in learning about your gun & it's workings. I have to say, I understand the correlation of the parts better than I did & I will apply that knowledge to my benefit &hopefully to the benefit of my firearm. Thanks!

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[armorer951]

Thanks, that's very kind. Even after 42+ years I still have much to learn......that's one of the reasons I'm here.

At the top of the "S&W - Smithing" forum page, there are a couple of great sources of information listed as "Stickys".....the FAQ and the Notable thread index. Links are listed below......

If you are interested in learning more about the internal working of the S&W revolvers, I would suggest picking up a copy of Jerry Kuhnhausen's book, The S&W Revolvers, A Shop Manual. 5th edition. It's full of high quality illustrations, schematics, and other information. Well worth the money.

FAQ thread link:
http://smith-wessonforum.com/s-w-smithing/94072-faqs.html

Notable link:
http://smith-wessonforum.com/s-w-smithing/166160-notable-thread-index.html

 

[simmitt]

push off

I just checked on what date smith would do refinish work on. 72 falls in the year that they will take back and re work. Do as u wil but for a phone call and sending it back for a safety issue, I bet smith will repair for no cost, its worth the call.

 

[Bpx4st]

I just checked on what date smith would do refinish work on. 72 falls in the year that they will take back and re work. Do as u wil but for a phone call and sending it back for a safety issue, I bet smith will repair for no cost, its worth the call.

I'll do that! Thanks for the info.

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[Bpx4st]

Thanks, that's very kind. Even after 42+ years I still have much to learn......that's one of the reasons I'm here.

At the top of the "S&W - Smithing" forum page, there are a couple of great sources of information listed as "Stickys".....the FAQ and the Notable thread index. Links are listed below......

If you are interested in learning more about the internal working of the S&W revolvers, I would suggest picking up a copy of Jerry Kuhnhausen's book, The S&W Revolvers, A Shop Manual. 5th edition. It's full of high quality illustrations, schematics, and other information. Well worth the money.

FAQ thread link:
http://smith-wessonforum.com/s-w-smithing/94072-faqs.html

Notable link:
http://smith-wessonforum.com/s-w-smithing/166160-notable-thread-index.html

As the old saying goes..."you only stop learning when you're dead", I have a long way to go before I know it all & hopefully, a long time to take as much in as I can.
I downloaded the manual for my particular model but it doesn't go into a great deal of "smithing", which I guess, is really a good thing. From what I've seen, it's a very involved & precise trade...& a bit costly. I'm a bit old (& broke) to take on the trade but maybe I can learn enough to recognize what I don't know & I won't screw something up. Lol

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[Bpx4st]

As the old saying goes..."you only stop learning when you're dead", I have a long way to go before I know it all & hopefully, a long time to take as much in as I can.
I downloaded the manual for my particular model but it doesn't go into a great deal of "smithing", which I guess, is really a good thing. From what I've seen, it's a very involved & precise trade...& a bit costly. I'm a bit old (& broke) to take on the trade but maybe I can learn enough to recognize what I don't know & I won't screw something up. Lol

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As the old saying goes...
I took my own advice & decided to "educate" myself on the inner workings. I thought about the dirt & crud issue brought up by armorer951 & with the help of the manual (to name the parts) & select YouTube videos (thanks Jerry M. & Harry P.), I dove in. Not overly cruddy but dirtier than I liked, so...
Long story short, you definitely learn from your mistakes but learn I did...& in a good way. After a couple of goofs (hand return spring, trigger tension spring [still not sure of names but I know what I mean]), I got it cleaned, lubed & back together & working fine. The main spring had a major bow to it but a little straightening, even helped with push-off & trigger action.
I would never try anything on a gun but my own but I believe in hands-on learning...even with an expensive risk. Thank God & good information, it worked!
Whew!



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